Robot cleaner and method for controlling the same

ABSTRACT

Disclosed are a robot cleaner and a method for controlling the same, capable of controlling a travelling or cleaning pattern of a robot cleaner in accordance with extension and retraction operations of an auxiliary cleaning tool to perform an efficient cleaning operation. The robot cleaner includes a plurality of auxiliary cleaning units mounted to a bottom of the robot cleaner such that the auxiliary cleaning units are extendable and retractable, and a control unit to extend the auxiliary cleaning units while travelling in a wall tracing manner along the periphery of the cleaning region and/or when an obstacle is sensed, and to retract the auxiliary cleaning units while the robot cleaner travels in an inner portion of the cleaning region when traveling of the periphery of the cleaning region is finished.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation Application of U.S. application Ser.No. 13/652,853, filed on Oct. 16, 2012, which claims the benefit ofKorean Patent Application Nos. 10-2011-0106698 and 10-2012-0022328,filed on Oct. 18, 2011 and Mar. 5, 2012, respectively, in the KoreanIntellectual Property Office, the disclosures of which are incorporatedherein by reference.

BACKGROUND

1. Field

Embodiments of the present disclosure relate to a robot cleanerincluding an auxiliary cleaning tool to perform an efficient cleaningoperation and a method for controlling the same.

2. Description of the Related Art

A robot cleaner automatically cleans a region by sucking foreign mattersuch as dust from a floor of the cleaning region while autonomouslytraveling about the cleaning region without being operated by a user.

A robot cleaner senses an obstacle or wall disposed within a cleaningregion, using various sensors, and controls a travel path and a cleaningoperation, based on the sensing result.

The robot cleaner repeatedly performs a cleaning task while traveling ona floor in accordance with a predetermined travel pattern. When there isan obstacle or wall in a cleaning region, it may be difficult for a mainbrush to reach a portion of the floor contacting the obstacle or wall.As a result, cleaning may be ineffectively achieved.

To this end, the robot cleaner is equipped with auxiliary cleaningtools, which are outwardly protruded from the robot cleaner. Suchauxiliary cleaning tools are mounted to opposite sides of a cleaner bodyand sweep dust or the like on the floor into the cleaner body whilerotating.

However, a robot cleaner of the related art has a problem in that itcannot perform an efficient cleaning operation since the operation ofauxiliary cleaning tools is not controlled in accordance with the travelpattern of the robot cleaner.

SUMMARY

Therefore, it is an aspect of the present disclosure to provide a robotcleaner and a method for controlling the same, capable of controlling atravelling or cleaning pattern of a robot cleaner in accordance withextension and retraction operations of an auxiliary cleaning tool toperform an efficient cleaning operation.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be obvious from the description, or may belearned by practice of the invention.

In accordance with one aspect, provided is a robot cleaner for removingforeign matter from a floor while traveling on the floor, including: aplurality of auxiliary cleaning units mounted to a bottom of the robotcleaner such that the auxiliary cleaning units are extendable andretractable; an obstacle sensor to sense an obstacle in a cleaningregion of the robot cleaner; and a control unit to extend the auxiliarycleaning units while travelling in a wall tracing manner along theperiphery of the cleaning region, and to retract the auxiliary cleaningunits while the robot cleaner travels in an inner portion of thecleaning region when traveling of the periphery of the cleaning regionis finished.

The control unit may extend only the auxiliary cleaning unit present onthe wall surface among the auxiliary cleaning units.

The control unit may control a speed of the robot cleaner that travelsin a wall tracing manner lower than a speed of the robot cleaner thattravels in an inner portion of the cleaning region.

The sensing unit may include: an obstacle sensor that senses obstaclesdisposed in the cleaning region and is implemented by one or more of anultrasonic sensor, a proximity sensor and an optical sensor; and a dustsensing unit that senses dust present on the floor of the cleaningregion and is implemented by an optical sensor.

The control unit may increase a cleaning speed of the auxiliary cleaningunits, when the obstacle sensor senses a wall disposed in front thereofwhile the robot cleaner travels in a wall tracing manner.

The control unit may repeat extension and retraction of the auxiliarycleaning units at predetermined intervals when an amount of dust sensedby the dust sensing unit is a predetermined reference value or more.

In accordance with another aspect, provided is a robot cleaner forremoving foreign matter from a floor while traveling on the floor,including: a plurality of auxiliary cleaning units mounted to a bottomof the robot cleaner such that the auxiliary cleaning units areextendable and retractable; an obstacle sensor to sense obstacles ordust in a cleaning region of the robot cleaner; and a control unit toset a first cleaning mode or a second cleaning mode based on the usercommand or the sensing results of the sensing unit, and control anoperation of the robot cleaner in accordance with the set cleaning mode,wherein the first cleaning mode is a cleaning mode that cleans even aportion in which the obstacle contacts the floor by extending theauxiliary cleaning units when the sensing unit senses obstacles, and thesecond cleaning mode is a cleaning mode that rapidly cleans byretracting the auxiliary cleaning units when the sensing unit senses theobstacles.

The sensing unit may include: an obstacle sensor that senses obstaclesdisposed in the cleaning region and is implemented by one or more of anultrasonic sensor, a proximity sensor and an optical sensor; and a dustsensing unit that senses dust present on the floor of the cleaningregion and is implemented by an optical sensor.

The second cleaning mode may extend the auxiliary cleaning units whenthe sensing unit does not sense the obstacles.

The robot cleaner may further include: an input unit to receive aselection command of the cleaning mode from a user, wherein the controlunit controls an operation of the robot cleaner in accordance with thecleaning mode selected via the input unit.

The control unit may control the robot cleaner to perform test travel inorder to calculate the number of obstacles present in the cleaningregion when a cleaning start command is input, and the sensing unit maysense obstacles present in the cleaning region during test travel andmay transmit the sensing results to the control unit.

The control unit may calculate the number of obstacles present in thecleaning region based on the sensing results of the sensing unit and maycontrol operations of the robot cleaner in accordance with the secondcleaning mode, when the calculated number of obstacles is apredetermined reference value or more and may control operations of therobot cleaner in accordance with the first cleaning mode, when thecalculated number of obstacles is lower than the predetermined referencevalue.

The control unit may repeat extension and retraction of the auxiliarycleaning units at predetermined intervals when an amount of dust sensedby the dust sensing unit is a predetermined reference value or more.

In accordance with another aspect, provided is a method for controllinga robot cleaner including extendably and retractably mounted auxiliarycleaning units, including: determining whether the robot cleaner travelsin a wall tracing manner when a cleaning start command is input;outwardly extending the robot cleaner when the robot cleaner travels ina wall tracing manner; determining whether the wall tracing travel ofthe robot cleaner is finished; and retracting the auxiliary cleaningunits when travel of the wall tracing manner is finished.

The control unit may extend only the auxiliary cleaning units present onthe wall surface among the auxiliary cleaning units, when the robotcleaner travels in a wall tracing manner.

The control unit may control a speed of the robot cleaner that travelsin a wall tracing manner lower than a speed of the robot cleaner thattravels in an inner portion of the cleaning region.

The method may further include: sensing obstacles disposed in front ofthe robot cleaner, wherein a cleaning speed of the auxiliary cleaningunits is increased, when a wall disposed in front of the robot cleaneris sensed while the robot cleaner travels in a wall tracing manner.

The method may further include: sensing dust disposed in the cleaningregion; and repeating extension and retraction of the auxiliary cleaningunits at predetermined intervals when an amount of dust sensed by thedust sensing unit is a predetermined reference value or more.

In accordance with another aspect, provided is a method for controllinga robot cleaner including extendably and retractably mounted auxiliarycleaning units, including: setting a first cleaning mode or a secondcleaning mode based on a user command or the sensing results of theobstacle; extending the auxiliary cleaning units when obstacles aresensed in a cleaning region to be cleaned by the robot cleaner, andretracting the auxiliary cleaning units when obstacles are not sensed ina cleaning region to be cleaned by the robot cleaner in a case in whichthe first cleaning mode is set; and retracting the auxiliary cleaningunits when obstacles are sensed in a cleaning region to be cleaned bythe robot cleaner and extending the auxiliary cleaning units whenobstacles are not sensed in a cleaning region to be cleaned by the robotcleaner in a case in which the second cleaning mode is set.

The method may further include: sensing obstacles present in thecleaning region of the robot cleaner; and calculating the number ofobstacles based on the sensing results, wherein operations of the robotcleaner are controlled in accordance with the second cleaning mode, whenthe calculated number of obstacles is a predetermined reference value ormore.

Extension and retraction of the robot cleaner may be repeated atpredetermined intervals, when dust present in the cleaning region of therobot cleaner is sensed and an amount of the sensed dust is apredetermined reference value or more.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings of which:

FIG. 1 shows a perspective view of a robot cleaner according to oneembodiment;

FIG. 2 shows a bottom view of the robot cleaner according to theillustrated embodiment;

FIG. 3 is a view schematically illustrating one embodiment associatedwith the structure of enabling each auxiliary cleaning unit to beextendable and retractable;

FIG. 4 is a view schematically illustrating the other embodimentassociated with the structure of enabling each auxiliary cleaning unitto be extendable and retractable;

FIG. 5 is a view schematically illustrating a configuration of theauxiliary cleaning tool according to one embodiment;

FIG. 6 is a view schematically illustrating a configuration of theauxiliary cleaning tool according to another embodiment;

FIG. 7 shows a block diagram of a control configuration of the robotcleaner according to one embodiment.

FIGS. 8A and 8B illustrate an overall configuration of travel andcleaning operations of the robot cleaner according to one embodimentwhen viewed from above.

FIG. 9 is a view illustrating a robot cleaner disposed at theintersection between two walls;

FIG. 10 is a view illustrating a case in which only the auxiliarycleaning tool disposed on the wall is extended in the robot cleanerillustrated in FIGS. 8A and 8B;

FIG. 11 is a block diagram illustrating a detailed control configurationof a travel control unit of the robot cleaner according to oneembodiment;

FIG. 12 is an image showing the robot cleaner according to oneembodiment;

FIG. 13 is a sectional view illustrating an example of an actually madecharacteristic map;

FIG. 14 illustrates an example of an actually made path map;

FIG. 15 is a view illustrating an operation of the robot cleanerillustrated in FIGS. 8A and 8B travelling in an excessively dustyregion;

FIG. 16 is a plan view from above illustrating operations of the robotcleaner performing a cleaning operation in a first cleaning mode;

FIG. 17 is a plan view from above illustrating operations of the robotcleaner performing a cleaning operation in a second cleaning mode;

FIGS. 18A and 18B are plan views from above, illustrating operation ofthe robot cleaner according to an embodiment that enters an excessivelydusty region;

FIG. 19 is a flowchart illustrating a method for controlling the robotcleaner according to the embodiment described in FIGS. 8A and 8B;

FIG. 20 is a flowchart illustrating a control method when the robotcleaner according to the embodiment described in FIGS. 8A and 8B facesthe wall while travelling in a wall tracing manner;

FIG. 21 is a flowchart briefly illustrating a control method when therobot cleaner according to the embodiment described in FIGS. 8A and 8Bpasses an excessively dusty region; and

FIG. 22 is a flowchart illustrating a method for controlling the robotcleaner according to the embodiment described in FIGS. 18A and 18B.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiments, examples ofwhich are illustrated in the accompanying drawings, wherein likereference numerals refer to the like elements throughout. Theembodiments are described below to explain the present disclosure byreferring to the figures.

Hereinafter, embodiments of the present disclosure will be describedwith reference to the accompanying drawings.

Referring to FIGS. 1 and 2, the robot cleaner, which is designated byreference numeral 1, includes a body 10 to define an outer appearance ofthe robot cleaner 1, a main brush unit 30 to sweep dust on a floor suchthat the swept dust is guided to a suction inlet, a power supply 50 tosupply drive power to drive the body 10, drive wheels 41 and 42 and acaster 43 to drive the body 10, and auxiliary cleaning units 100 a and100 b to clean areas of the floor disposed adjacent to a wall and edgeareas of the floor.

The drive wheels 41 and 42, are centrally arranged at opposite sides ofa bottom of the body 10 in a symmetrical manner, respectively. The drivewheels 41 and 42 may perform movement operations including forwardmovement, backward movement, and rotation during execution of cleaning.

The caster 43 is installed at a front edge portion of the bottom of thebody 10 when viewed on the basis of a travel direction. The caster 43varies a rotation angle thereof in accordance with the state of thefloor, on which the robot cleaner 1 travels, to allow the body 10 tokeep a stable posture. The drive wheels 41 and 42, and caster 43 may beconfigured into a single assembly detachably mounted to the body 10.

The power supply 50 includes a battery electrically connected to thebody 10 and drivers to drive various elements mounted to the body 10, tosupply drive power to the body 10 and drivers. The battery isconstituted by a rechargeable secondary battery. When the body 10 iscoupled to a docking station (not shown) after completing a cleaningoperation, the battery receives electric power from the docking station,to be charged.

The main brush unit 30 is mounted at an opening formed at a portion ofthe bottom of the body 10 biased from a central region of the body 10 ina rear direction R.

The main brush unit 30 removes foreign matter such as dust accumulatedon the floor, on which the body 10 is disposed. The opening of thebottom of the body 10, at which the main brush unit 30 is mounted,functions as a dust inlet 33.

The main brush unit 30 includes a roller 31, and a main brush 32 stuckin an outer surface of the roller 31. As the roller 31 rotates, the mainbrush 32 sweeps dust accumulated on the floor such that the swept dustis guided to the dust inlet 33. The roller 31 may be made of steel, butembodiments of the present invention are not limited thereto. The mainbrush 32 may be made of various materials having elasticity.

Although not shown, a fan unit to generate suction force is providedwithin the dust inlet 33. The fan unit functions to move dust introducedinto the dust inlet 33 to a dust collector 55.

A sensing unit 60 is mounted to the body 10, to sense the surroundingsof the robot cleaner 1. The sensing unit 60 may include a proximitysensor 61 and/or a vision sensor 62. For example, when the robot cleaner1 travels in a random direction under the condition that there is nopredetermined path, along which the robot cleaner 1 travels, that is, ina cleaning system having no map, the robot cleaner 1 may travel about acleaning region, using the proximity sensor 61. On the other hand, whenthe robot cleaner 1 travels along a predetermined path, that is, in acleaning system requiring a map, the vision sensor 62 may be installedto receive position information of the robot cleaner 1, and thus tocreate a map. The sensing unit 60 may be implemented in various manners.

A display unit 65 is provided to display various states of the robotcleaner 1. For example, the display unit 65 may display a charged stateof the battery, whether or not the dust collector 55 is full of dust, amode of the robot cleaner, for example, a cleaning mode or a dormantmode, etc.

Although not shown, the robot cleaner may include an input unit toreceive commands associated with various modes such as a travel mode anda cleaning mode, power on/off commands, etc. in accordance with anembodiment of the present invention.

Hereinafter, the configuration and structure of auxiliary cleaning unit100 a or 100 b included in the robot cleaner according to theillustrated embodiment will be described with reference to FIGS. 3 to 6.

Each auxiliary cleaning unit 100 a or 100 b is mounted to the bottom ofthe robot cleaner such that it is extendable and retractable. Thestructure, which enables the auxiliary cleaning unit to be extendableand retractable, may be implemented through various embodiments. In thefollowing description, two embodiments will be described.

FIG. 3 is a view schematically illustrating one embodiment associatedwith the structure of enabling each auxiliary cleaning unit to beextendable and retractable. The auxiliary cleaning unit 100 will berepresented without distinguishing the left auxiliary cleaning unit 100b from the right auxiliary cleaning unit 100 a below, since the left andright auxiliary cleaning units may have an identical basic structure.

Referring to FIG. 3, each auxiliary cleaning unit 100 a or 100 bincludes a side arm 102 and a periphery cover 103.

The side arm 102 is coupled to a front portion of the bottom of the body10 at one side of the body 10. An arm motor (not shown) is received inthe body 10 over the side arm 102, to drive the side arm 102. The armmotor is connected to a rotation shaft (not shown) via gears to transmitdrive force to the side arm 102. The rotation shaft is mounted to acoupling groove 101 formed at one end of the side arm 102.

When the arm motor drives, the rotation shaft is rotated, therebycausing the side arm 102 to pivot about the coupling groove 101. In thiscase, the side arm 102 pivots outwardly of the body 10. In this state,the periphery cover 103 no longer covers the opening of the body 10.That is, the periphery cover 102 no longer forms the periphery of thebody 10.

A coupling groove 104, to which an auxiliary cleaning tool is coupled,is formed at the other end of the side arm 102. A rotation motor (notshown) is received in the body over the coupling groove 104, to drivethe auxiliary cleaning tool. The auxiliary cleaning tool is rotatedabout the coupling groove 104 by drive force of the rotation motor.

FIG. 4 is a view schematically illustrating the an embodiment associatedwith the structure of enabling each auxiliary cleaning unit to beextendable and retractable.

Referring to FIG. 4, each auxiliary cleaning unit 100 a or 100 bincludes a side arm 106 and a periphery cover 108.

The side arm 106 is coupled to a front portion of the bottom of the body10 at one side of the body 10 via a coupling groove 105. An extensionarm 107 is received in the side arm 106 such that it is extendableoutwardly of the side arm 106 in a sliding manner.

The extension arm 107 moves forward and rearward within the side arm 106in a longitudinal direction of the side arm 106. To this end, a rail isformed within the side arm 106, and a guide (not shown), which isengaged with the rail, is formed at the extension arm 107. Accordingly,the extension arm 107 may slidably move along the rail in a state ofbeing coupled to the rail. Another extension arm may be received in theextension arm 107 such that it is extendable outwardly of the extensionarm 107 in a sliding manner. Meanwhile, the movement of the anotherextension arm may be carried out in the same manner as described above.There is no limitation as to the number of extension arms.

An arm motor (not shown) is received in the body 10 over the side arm106, to drive the side arm 106. The arm motor transmits drive force tothe extension arm 107 via gears. When the arm motor drives, theextension arm 107 slides outwardly of the side arm 106, to extendoutwardly of the body 10. In this state, the periphery cover 108 nolonger covers the opening of the body 10. That is, the periphery cover108 no longer forms the periphery of the body 10.

A coupling groove 109, to which an auxiliary cleaning tool is coupled,is formed at one end of the extension arm 107. A rotation motor (notshown) is received in the body over the coupling groove 109, to drivethe auxiliary cleaning tool. The auxiliary cleaning tool is rotatedabout the coupling groove 109 by drive force of the rotation motor.

The auxiliary cleaning tool, which is also included in the auxiliarycleaning unit, carries out cleaning. The auxiliary cleaning tool mayinclude a brush to sweep or disperse foreign matter such as dust, afloorcloth to wipe the floor, or a suction device to suck foreign mattersuch as dust. Of course, these examples are illustrative and, as such,there is no limitation as to the kind of the auxiliary cleaning toolapplied to the embodiments as long as the auxiliary cleaning toolcarries out auxiliary cleaning.

FIG. 5 is a view schematically illustrating a configuration of theauxiliary cleaning tool according to an exemplary embodiment.

Referring to FIG. 5, the auxiliary cleaning tool, which is designated byreference numeral 110, includes brush arms 113 coupled to form a centralcommon end such that they outwardly extend in a radial direction fromthe central common end while being spaced apart from one another in acircumferential direction. An auxiliary brush 112 is coupled to eachbrush arm 113. A rotation shaft 114 is formed at the central common endof the brush arms 113. The rotation shaft 114 extends to be coupled tothe side arm 102 or extension arm 106 via the coupling groove 109. Whenthe auxiliary cleaning tool 110 rotates, the auxiliary brush 112 sweepsdust accumulated on an area disposed adjacent to a wall toward thecentral region of the body 10 or disperses the dust.

FIG. 6 is a view schematically illustrating a configuration of theauxiliary cleaning tool according to an embodiment.

Referring to FIG. 6, the auxiliary cleaning tool 110 includes a circularfloorcloth holder 116. An auxiliary floorcloth 115 is fitted around thefloorcloth holder 116 in a radial direction. A rotation shaft 114 isformed at a center of the floorcloth holder 116 such that it axiallyextends. The rotation shaft 114 receives drive force from a rotationmotor, to rotate the auxiliary cleaning tool 110. The rotation shaft 114is coupled to the side arm 102 or extension arm 106 via the couplinggroove. When the auxiliary cleaning tool 110 rotates, the auxiliaryfloorcloth 115 scrubs an area disposed adjacent to a wall.

When the embodiment of FIG. 6 is applied together with the embodiment ofFIG. 4, the cleaning operation of the auxiliary cleaning unit 100 mayinclude not only rotation of the auxiliary cleaning tool 110, but alsorepeated extension and retraction of the extension arm 106. Otherwise,the cleaning operation may be carried out only through repeatedextension and retraction of the extension arm 106 without rotation ofthe auxiliary cleaning tool 110.

Meanwhile, the auxiliary brush 112 may be made of various materialshaving elasticity. The auxiliary floorcloth 115 may be made of a fibermaterial or various materials other than the fiber material.

The robot cleaner 1 according to the illustrated embodiment may cleaneven an area of the floor disposed adjacent to a wall or an edge area ofthe floor, because the effective cleaning region of the robot cleaner 1is extended by virtue of the auxiliary cleaning units 100 a and 100 boutwardly extendable from the body 10.

Although two auxiliary cleaning units 100 are provided at opposite sidesof the robot cleaner 1, respectively, in the embodiments of FIGS. 1 to6, embodiments are not limited thereto. There is no limitation as to thenumber of auxiliary cleaning units 100 and the mounting positions ofauxiliary cleaning units 100. Of course, for convenience of description,the following embodiments will be described in conjunction with the casein which two auxiliary cleaning units 100 are provided at opposite sidesof the robot cleaner 1, respectively, as in the embodiments of FIGS. 1to 6. Also, for convenience of description, the following descriptionwill be given only in conjunction with one auxiliary cleaning unit 100because the two auxiliary cleaning units 100 have the sameconfiguration.

Hereinafter, travel and cleaning operations of the robot cleaner 1according to the illustrated embodiment carried out on the basis of theabove-described configuration will be described in detail.

In the following embodiments, it is assumed that cleaning by the mainbrush unit is basically carried out during travel of the robot cleaner.

Although the auxiliary cleaning tool 110, which is applicable toembodiments, may be implemented in various forms such as a brush and afloorcloth, as described above, the following embodiments will bedescribed in conjunction with the case in which the auxiliary cleaningtool 110 is implemented in the form of a brush, for convenience ofdescription.

FIG. 7 shows a block diagram of a control configuration of the robotcleaner according to an exemplary embodiment of the present invention.

Referring to FIG. 7, in accordance with the illustrated embodiment ofthe present invention, the robot cleaner 1 includes a sensing unit 60 tosense the state of the auxiliary cleaning unit 100 and the surroundingsof the robot cleaner 1, an input unit 70 to receive a command from theuser in association with travel or cleaning operation of the robotcleaner 1, and a control unit 200 to control the travel and cleaningoperation of the robot cleaner 1 in accordance with the sensing resultof the sensing unit 60 or the command input to the input unit 70. Themain brush unit 30 and auxiliary cleaning unit 100 to perform thecleaning operation of the robot cleaner 1 are also included in the robotcleaner 1. The robot cleaner 1 further includes a travel unit 40 toperform the travel of the robot cleaner 1.

The sensing unit 60 senses obstacles adjacent thereto while the robotcleaner 1 moves. The sensing unit 60 may be realized by an ultrasonicsensor, an optical sensor or a proximity sensor. The sensing unit 60realized by an ultrasonic sensor transmits ultrasonic waves to a travelpath and receives the reflected ultrasonic wave to sense obstacles. Inthe sensing unit 60 realized by an optical sensor, an infrared-emittingdevice emits an infrared ray and an infrared-receiving device receivesthe reflected infrared ray to sense obstacles. Further, proximitysensors, contact sensors or the like may be used and the configurationthereof is not limited so long as it can sense obstacles.

The input unit 70 receives a command from the user in association withtravel or cleaning operation of the robot cleaner 1. Basically, acleaning start command or a cleaning finish command may be input throughon/off input. Also, commands respectively associated with a travel modeand a cleaning mode may be input. The input unit 70 is provided at thebody 10 of the robot cleaner 1. The input unit 70 may be implemented inthe form of buttons. Alternatively, the input unit 70 may be implementedin the form of a touch panel provided at the display unit 65.

The control unit 200 controls the overall operation of the robot cleaner1 and broadly includes a cleaning controller 210 to control the mainbrush unit 30 and a travel control unit 220 to control travel.

The cleaning controller 210 controls the main brush unit 30 and theauxiliary cleaning unit 100 according to the cleaning mode set based onthe sensing results of the sensing unit 60 or user commands input viathe input unit 70.

The travel control unit 220 controls the travel unit 40 according to thecleaning mode set based on the sensing results of the sensing unit 60 oruser commands input via the input unit 70 and thereby controls a traveldirection and a travel speed of the robot cleaner 1.

Detailed operations of the cleaning controller 210 and the travelcontrol unit 220 will be described below.

As described above, the main brush unit 30 includes the roller 31, andthe main brush 32 stuck in the outer surface of the roller 31. As theroller 31 rotates, the main brush 32 sweeps dust accumulated on thefloor such that the swept dust is guided to the dust inlet 33. Thus,main cleaning operation is carried out. When the cleaning controller 210sends a control signal to the drive motor to drive the roller 31, themain brush 32 performs cleaning operation in accordance with the controlsignal.

The auxiliary cleaning unit 100 performs cleaning of an edge area, forwhich it is difficult to achieve effective cleaning, using the mainbrush unit 30. The auxiliary cleaning unit 100 includes the side arm 102or 106 and/or the extension arm 107, which extends or retracts theauxiliary cleaning tool 110, the rotation motor to rotate the auxiliarycleaning tool 110, and the arm motor to drive the side arm 102 or 106and/or the extension arm 107.

As described above, the travel unit 40 includes the drive wheels 41 and42, the caster 43, and the driver to drive the drive wheels 41 and 42.The travel control unit 230 sends a control signal to the driver, todrive the drive wheels 41 and 42 forward or rearward, and thus to movethe robot cleaner 1 forward or rearward. Meanwhile, during rearwarddriving of the left drive wheel 41 or 42, it may be possible to turn therobot cleaner 1 to the left when viewed in front of the robot cleaner 1by forwards driving the right driver wheel 42 or 41. Through driving ofthe drive wheels 41 and 42 in a reverse manner to the above-describedcase, it may be possible to turn the robot cleaner 1 to the right whenviewed in front of the robot cleaner 1.

Hereinafter, the operation of the robot cleaner 1 according to anembodiment will be described.

FIGS. 8A and 8B show an overall configuration of travel and cleaningoperations of the robot cleaner 1 according to an embodiment when viewedfrom above.

When a user inputs a cleaning start command through the input unit 70,the robot cleaner 1 starts travel and cleaning operations. At this time,the travel mode of the travel control unit 220 may be set to walltracing travel along the periphery of the cleaning region and then arandom or predetermined travel inside the cleaning region.

Referring to FIG. 8A, when the robot cleaner 1 according to oneembodiment of the present invention travels about the periphery of thecleaning region in a wall tracing manner, cleaning is not completelyperformed, since it is difficult for the brush 32 of the main brush unit30 to reach an area of the floor disposed adjacent to a wall or an edgearea of the floor. Also, the area of the floor disposed adjacent to awall is a region in which dust is readily deposited, thus requiringaccurate cleaning. Accordingly, when the robot cleaner 1 travels in awall tracing manner, the auxiliary cleaning unit 100 is extendedoutwardly to clean the area of the floor disposed adjacent to a wall.

Referring to FIG. 8B, after the robot cleaner 1 according to oneembodiment of the present invention finishes wall tracing travel in theperiphery of the cleaning region, it starts travel in the cleaningregion. In this case, the travel manner may be a zigzag travel mode, asshown in FIG. 8B, or other patterned travel or random travel.

Also, the inner part of the cleaning region may be an area, excluding aregion which cleaning is completed by wall tracing travel, as shown inFIG. 8A, or an area including the region in which cleaning is completedby wall tracing travel. Through the former, it may be possible torealize complete cleaning within a short time, while, through thelatter, it may be possible to realize accurate cleaning.

When the robot cleaner 1 travels about the inner part of the cleaningregion, the extended auxiliary cleaning tools 110 is retracted. Theinner part of the cleaning region has no edge that does not come incontact with the main brush 32. Accordingly, only using the main brushunit 30, it is possible to perform sufficient cleaning without using theauxiliary cleaning unit 100. If the robot cleaner 1 encounters anobstacle in the inner part of the cleaning region, the auxiliarycleaning tools 110 may be extended to clean around the edge of theobstacle.

Also, the auxiliary cleaning tools 110 may be rotated in a state thatthe auxiliary cleaning unit 100 is retracted. In this case, when aportion that does not contact the main brush unit 30 is present in aregion in which the robot cleaner 1 travels, cleaning can be performedin the portion.

The travel path or pattern shown in FIGS. 8A and 8B is provided only forone embodiment. Regardless of the overall travel path or travel patternof the robot cleaner 1, the wall tracing travel pattern extends theauxiliary cleaning unit 100 and other travel manner such as zigzagtravel or random travel retracts the auxiliary cleaning tool 110.

Referring to FIG. 9, cleaning is not completely performed by the mainbrush 32 and dust is readily deposited at the intersection between twowalls due to the structure of the robot cleaner 1.

Accordingly, when the robot cleaner 1 is deposited at the intersectionbetween two walls while travelling in a wall tracing manner, efficientcleaning may be performed within a predetermined time by increasing therotation speed of the auxiliary cleaning tools 110. For reference, whenthe auxiliary cleaning unit 100 is realized by combination of theembodiments of FIGS. 4 and 6, efficient cleaning can be performed byincreasing a cleaning speed of the auxiliary cleaning tools 110. Here,the term “cleaning speed” may be determined by considering an extensionand retraction repetition speed of the extension arm 107 or a rotationspeed of the auxiliary cleaning tools 110 and the extension andretraction repetition speed of the extension arm 107.

For this purpose, the sensing unit 60 transfers the obstacle sensingresults to the control unit 200 and the cleaning controller 210 analyzesthe sensing results and, as a result, when an obstacle is disposed infront of the robot cleaner 1 that travels in a wall tracing manner, acontrol signal to increase the rotation speed of the auxiliary cleaningtools 110 is transmitted to the auxiliary cleaning unit 100.

When a sensor that can sense only an obstacle adjacent to the robotcleaner 1 is used as the sensing unit 60, the rotation speed of theauxiliary cleaning tools 110 may be increased only according to thesensing results of the obstacle presence. However, in a case in which asensor that can sense an obstacle disposed by a long distance is used,when a distance that is sufficiently short to an extent that the robotcleaner 1 is considered to be disposed at the intersection between twowalls is set as a reference value and the distance between the obstacleand the robot cleaner 1 is the reference value or less based on thesensing results of the sensing unit 60, the rotation speed of theauxiliary cleaning tools 110 can be increased.

In the embodiment of FIG. 8A, both sides of the robot cleaner 1 isextended. As shown in FIG. 10, only the auxiliary cleaning tool presentat the wall side is extended and the remaining auxiliary cleaning toolis not extended.

Travel of the robot cleaner 1 as mentioned above may be based on thepredetermined path map or characteristic map, or a rotation or straighttravel manner may be randomly determined through determination ofpresence of obstacles without using the map.

Hereinafter, travel based on the path map or characteristic map will bedescribed in detail according to one embodiment.

FIG. 11 is a block diagram illustrating a detailed control configurationof a travel control unit 220 of the robot cleaner 1 according to oneembodiment of the present invention.

As described in FIG. 7 above, the robot cleaner 1 according to anembodiment includes a sensing unit 60 to sense the surroundings of therobot cleaner 1, an input unit 70 to receive a command from the user, acontrol unit 200 to control the travel and cleaning operation of therobot cleaner 1, a main brush unit 30, an auxiliary cleaning unit 100and a travel unit 40.

The sensing unit 60 includes an obstacle sensor 61 to sense obstaclessuch as ultrasonic sensor, optical sensor, or proximity sensor andfurther includes a vision sensor 62 to image a surrounding imagesuitable for extraction of characteristic points for production of apath map. The surrounding image may include ceiling, wall and floor andthe ceiling having the lowest possibility of image variation is the mostsuitable for the surrounding image. Hereinafter, an example in which theceiling is used for the surrounding image will be described.

The vision sensor 61 may be realized by a charge-coupled device (CCD), acomplementary metal oxide semiconductor (CMOS) or other imaging device.The vision sensor 61 may include an analog-to-digital converter (ADC)that converts an analog signal of the obtained image into a digitalsignal.

Also, the sensing unit 60 further includes a position recognition unit63 such as encoder, gyro sensor or acceleration sensor to recognize apresent position of the robot cleaner 1.

The encoder is connected to driving wheels 41 and 42 to sense a rotationspeed. By integrating the rotation speed sensed by the encoder, theposition (or moved distance) and orientation angle of the robot cleaner1 can be obtained. The gyro sensor measures an orientation angle of therobot cleaner 1 using rotational inertia. The acceleration sensor canmeasure the position of the robot cleaner 1 by double-integrating themovement acceleration speed of the robot cleaner 1.

The travel control unit 220 includes a characteristic map productionunit 221 to extract a plurality of characteristic points from theceiling image obtained from the vision sensor 62 and thereby produce acharacteristic map, a path map production unit 222 to produce a path mapof the robot cleaner 1 and a storage unit 223 to store the produced map.

The characteristic map production unit 221 extracts a plurality ofcharacteristic points from the ceiling image obtained from the visionsensor 62 and thereby produces a characteristic map. The characteristicmap includes characteristic points uniformly measured in thesurroundings. The characteristic points mean points in which inherentcharacteristics are exhibited at a specific position.

Referring to FIG. 12, the ceiling image 280 may include detailed imagesthat distinguish different positions, such as a chandelier 281, afluorescent light 282 or an edge portion 283. When characteristic pointsare represented in these detailed images, and the same characteristicpoints as the characteristic points represented in images obtained bythe moving robot cleaner 1 are then found, the posture (position andorientation angle) of the robot cleaner 1 can be seen.

FIG. 13 is a sectional view illustrating an example of an actually madecharacteristic map. The characteristic map 300 includes various shapesof characteristic points and adjacent characteristic points areconnected to one another. When a combination of characteristic pointspreviously defined in an image 350 photographed by the robot cleaner 1is found, the position and orientation angle of the robot cleaner 1 canbe seen. Meanwhile, as algorithm to extract the characteristic pointsdescribed above, scale invariant feature transforms (SIFTs),descriptors, Harris corner detectors. Imaging as well as other SLAMmethods such as radio frequency identification (RFID) and range findersusing structure light are used to generate the characteristic map. Here,SLAM is an algorithm for simultaneously performing position recognitionof the robot cleaner 1 and map production.

The characteristic map production unit 221 matches characteristic pointsobtained from the ceiling image with the positions measured by theposition recognition unit 63 to complete a characteristic map. When thecharacteristic map production unit 221 finishes production of thecharacteristic map, it can easily recognize the position and orientationangle of the robot cleaner 1 by comparing characteristic points from thephotographed image with the characteristic map.

The storage unit 223 stores the map produced in the characteristic mapproduction unit 221. The storage unit 223 may be implemented bynonvolatile memory devices such as ROM, RAM, PROM, EPROM and flashmemories, or volatile memory devices such as RAM, or storage media suchas hard disks and optical disks or any other forms known in the relatedart.

The path map production unit 222 produces a cleaning path map of therobot cleaner 1. Referring to FIG. 14, the path map production unit 222stores position data of the periphery of the cleaning region and therebyproduces a cleaning path map by moving the robot cleaner 1 along thewall. Specifically, the path map production unit 222 stores an initialposition, “P0”, stores data of edge position (P1 to P4) at which themovement direction is changed when the robot cleaner moves along thewall and sets P0 to P4 as the peripheral cleaning paths. The path mapproduction unit 222 divides cleaning blocks based on the initialposition (P0) and the edge positions (P1 to P4) and produces a cleaningpath so that the robot cleaner travels and cleans the cleaning blocks ina specific pattern. Here, the specific pattern means a regulated patternsuch as zigzag travel path, wall tracing path or spiral travel path andthe cleaning path may be a combination of a plurality of specificpatterns.

At this time, the operation of the auxiliary cleaning unit 100 of therobot cleaner 1 may be described in accordance with the cleaning pathset in the path map production unit 222. Referring to FIG. 8 describedabove, when the cleaning path produced by the path map production unitis a cleaning path shown in FIGS. 8A and 8B, travels of the peripheralportion and the inner portion of the cleaning region are previously setas extension and retraction of the auxiliary cleaning tools 110,respectively.

Accordingly, the auxiliary cleaning tools 110 extend or retract in atravel path of the robot cleaner, regardless of the sensing results ofthe obstacle sensor 61.

Also, the robot cleaner 1 according to an embodiment travels about theperipheral portion of the cleaning region at a lower speed, when ittravels about the inner portion of the cleaning region. The robotcleaner 1 may travel without using a map. When the robot cleaner 1travels using a map, it stores the map along with the travel path asdescribed above. The travel of the peripheral portion of the cleaningregion in accordance with a wall tracing manner may be set by extendingthe auxiliary cleaning tools 110 and decreasing a travel speed of therobot cleaner 1, or controlling a predetermined reference value or less.In this case, the time at which auxiliary cleaning tools 110 stays in anarea in which the wall contacts floor is lengthened and the robotcleaner can precisely clean even the edge.

FIG. 15 is a view illustrating an operation of the robot cleaner 1traveling in an excessively dusty region according to an embodiment.

In the robot cleaner 1 according to an embodiment, the sensing unit 60may further include a dust sensor to sense the amount of dust. The dustsensor is mounted on a dust inlet 33 such that a light emitting unit toemit light faces a light receiving unit to receive light, and the amountof dust can be seen by analyzing a power signal of the dust sensor,since the amount of light received by the light-receiving portion isvaried depending on the amount of dust.

As shown in FIG. 12, when the traveling robot cleaner 1 passes theexcessively dusty region, extension and retraction operations ofauxiliary cleaning tools 110 are repeated at predetermined intervals.Specifically, as the sensing results of the dust sensor are transportedto the control unit 200 and are analyzed by the cleaning controller 210,when the dust amount is a predetermined reference value or higher,extension and retraction operations of the auxiliary cleaning tools 110are repeated at predetermined intervals. The predetermined referencevalue is previously set by a user or a designer and the amount of dustthat cannot be completely cleaned in a general cleaning mode may be setbased on experiments or statistics.

The predetermined intervals at which extension and retraction operationsof auxiliary cleaning tools 110 are repeated may be also predeterminedby a user or a designer and, as the interval increases, efficiency ofcleaning improves.

Like the embodiment above, when the auxiliary cleaning tool 110 repeatsextension and retraction in the excessively dusty region, the auxiliarycleaning tool 110 informs a user of a dust-rich region and efficientlyrakes or disperses dust.

Hereinafter, operation of the robot cleaner 1 according to an embodimentwill be described.

The user wants to thoroughly clean even edges such as regions in whichwalls or obstacles contact the floor while cleaning using the robotcleaner 1 and often wants to clean the overall cleaning region within ashort time.

Also, in a case in which many obstacles or walls are present in thecleaning region, when the robot cleaner is rapidly traveled byretracting auxiliary cleaning tools 110 is more efficient than when theedge is cleaned by extending the auxiliary cleaning tools 110.

Accordingly, the robot cleaner 1 according to an embodiment divides acleaning mode into a first cleaning mode and a second cleaning mode andmay carry out cleaning in another cleaning mode according to the usercommand or environments of the cleaning region.

FIG. 16 is a plan view from above illustrating operations of the robotcleaner 1 cleaning in the first cleaning mode and FIG. 17 is a plan viewfrom above illustrating operations of the robot cleaner 1 cleaning inthe second cleaning mode.

Referring to FIG. 16, when the cleaning mode is set to the firstcleaning mode and a basic travel pattern of the robot cleaner 1 is azigzag manner, the robot cleaner 1 travels in a state in which theauxiliary cleaning tool 110 is retracted when the robot cleaner 1 doesnot meet with an obstacle, and the robot cleaner 1 cleans the edge atwhich the obstacle contacts the floor in a state in which the auxiliarycleaning tool 110 is extended when the robot cleaner 1 encounters anobstacle. At this time, the travel control unit 210 can perform morethorough cleaning by reducing the travel speed of the robot cleaner 1.Also, after the robot cleaner passes an obstacle, it retracts theauxiliary cleaning tools 110 and when the travel speed of the robotcleaner 1 is decreased, travel speed is increased again.

Referring to FIG. 17, when the cleaning mode is set to the secondcleaning mode and a basic travel pattern of the robot cleaner 1 is azigzag manner, the robot cleaner 1 cleans in a state in which theauxiliary cleaning tool 110 is extended when the robot cleaner 1 doesnot encounter an obstacle, and the robot cleaner 1 rapidly passes theobstacle without cleaning the edge in a state in which the auxiliarycleaning tool 110 is retracted ended and when the robot cleaner 1encounters an obstacle. After the robot cleaner passes obstacles, theauxiliary cleaning tool 110 is extended again.

When the robot cleaner 1 travels based on the path map, the width of thetravel path is set, while considering the size of the body so thatcomplete cleaning is realized. Referring to FIGS. 16 and 17, since acleaning region is considered in a state in which the auxiliary cleaningtools 110 are retracted, when cleaning is performed in the firstcleaning mode, the width of travel path is narrowly set, and since thecleaning region is considered in a state in which auxiliary cleaningtools 110 are extended, when cleaning is performed in the secondcleaning mode, the width of travel path is widely set.

Accordingly, although the predetermined region is cleaned, the firstcleaning mode performs travelling along nine lines and the secondcleaning mode performs travelling along eight lines. That is, the secondcleaning mode enables rapider cleaning. Also, the second cleaning modecan more thoroughly clean a region having no obstacle, since theauxiliary cleaning tools 110 are extended in the region having noobstacle.

However, since the first cleaning mode can clean even the edge ofobstacles, a user selects the first cleaning mode or the second cleaningmode via the input unit 70 and thereby performs desired cleaning.

Also, the robot cleaner 1 may autonomously select a cleaning mode. Whilethe robot cleaner 1 test-travels the cleaning region to photographsurrounding images, it senses obstacles present in the cleaning regionvia the sensing unit 60, counts the number of obstacles in the cleaningcontroller 210 and sets the second cleaning mode when the number is thepredetermined value or higher, and sets the first cleaning mode when thenumber is lower than the predetermined value.

A designer may set a predetermined reference value while taking intoconsideration efficiency of cleaning through experiments or statistics,and may set or change the value.

In the embodiment of FIGS. 16 and 17, the robot cleaner 1 travels abouta cleaning region in a zigzag pattern, but any travel pattern other thanthe zigzag pattern may be used in the embodiment shown in FIGS. 16 and17. In the embodiment of the present invention illustrated in FIGS. 8Aand 8B, cleaning of an inner part of the cleaning region may beperformed using the embodiment of FIGS. 16 and 17.

Also, like the embodiment of the present invention illustrated in FIGS.8A and 8B, the embodiment illustrated in FIGS. 16 and 17 may also beused in all cases in which the travel path is determined by the map andin which the travel path is not determined by the map.

Also, although a case in which the robot cleaner 1 cleans in the firstcleaning mode and the second cleaning mode is described in theembodiment of FIGS. 16 and 17, the robot cleaner 1 may clean in a thirdcleaning mode in which the auxiliary cleaning tools 110 are notextended.

The third cleaning mode is also selected through the input unit 70 orthe sensing unit 60 senses an obstacle present in the cleaning region,the control unit 200 counts the number of obstacles, and the thirdcleaning mode is set when the obtained number of obstacles is thepredetermined reference value or less. This case is based on the factthat sufficient cleaning is performed without extending the auxiliarycleaning tools 110, since many obstacles are not present in the cleaningregion. Otherwise, when the obtained number of obstacles is thepredetermined reference value or more, the third cleaning mode is set.This case is based on the fact that, when many obstacles are present inthe cleaning region, extension and retraction operations of theauxiliary cleaning tools 110 are excessively frequently repeated andcleaning speed may thus be decreased or power may be wasted. Theembodiment of FIGS. 16 and 17 includes both cases.

Also, the embodiment of the present invention may include all or a partof the first cleaning mode, the second cleaning mode and the thirdcleaning mode.

The embodiment of the present invention described in FIGS. 16 and 17 mayalso use extension and retraction operations of auxiliary cleaning tools110 in the excessively dusty region, as in the embodiment of FIGS. 8Aand 8B.

FIGS. 18A and 18B are plan views from above, illustrating operation ofthe robot cleaner 1 according to another embodiment of the presentinvention that enters an excessively dusty region.

Referring to FIGS. 18A and 18B, when the excessively dusty region ispresent in the travel path in all cases in which cleaning is performedin the first cleaning mode or the second cleaning mode, extension andretraction of auxiliary cleaning tools 110 are repeated at predeterminedintervals while the robot cleaner 1 travels about the excessively dustyregion, thereby efficiently sweeping or dispersing excess dust andinforming a user of the excessively dusty region. As described above,the cleaning controller 210 controls such that auxiliary cleaning tools110 repeat extension and retraction, when the amount of dust sensed bythe dust sensor is a predetermined reference value or more.

Hereinafter, a method for controlling the robot cleaner 1 according to aembodiment will be described.

FIG. 19 is a flowchart illustrating a method for controlling the robotcleaner 1 according to the embodiment described in FIGS. 8A and 8B.

Referring to FIG. 19, first, whether a cleaning start command is inputis determined (410), and a travel pattern of the robot cleaner 1 isdetermined, when the cleaning start command is input (YES in 410) (420).The wall tracing travel means that travel is performed along theperipheral portion of the cleaning region.

As a result of determination, when the robot cleaner 1 travels in a walltracing manner (YES in 430), the auxiliary cleaning tools 110 areextended outwardly of the body of the robot cleaner 1 (440). For thisreason, the auxiliary cleaning tools 110 reach even the edge at whichthe wall contacts the floor and thorough cleaning can thus be performed.

At this time, all auxiliary cleaning tools 110 present at both sides ofthe robot cleaner 1 may be extended and only the auxiliary cleaning tool110 present on the wall may be extended.

Also, when the robot cleaner 1 travels in a wall tracing manner, thetravel speed may be adjusted to a relatively low level. Here, the term“relatively low level” means that the travel speed is lower than a basictravel speed or a travel speed of other travel pattern of the robotcleaner 1. By adjusting the travel speed to a low level, a time at whichthe auxiliary cleaning tool 110 stays in the edge is lengthened andthorough cleaning can thus be performed.

Whether or not wall tracing travel is finished is determined (YES in450). As a result of determination, when the wall tracing travel is notfinished, the auxiliary cleaning tool 110 keeps the extension state andwhen the wall tracing travel is finished, the auxiliary cleaning tool110 is retracted (460).

In the embodiment above, the travel pattern of the robot cleaner 1 mayinclude wall tracing as well as zigzag or random and travel of the robotcleaner 1 may be performed with or without a path map.

FIG. 20 is a flowchart illustrating a control method when the robotcleaner 1 according to the embodiment described in FIGS. 8A and 8B facesthe wall while travelling in a wall tracing manner.

The operations including determination as to whether or not a cleaningstart command is input (510) to extension of the auxiliary cleaningtools 110 (540) are described in FIG. 19 above and a detaileddescription thereof will be thus omitted.

When the robot cleaner 1 senses presence of a wall in front thereofwhile travelling in a wall tracing manner (YES in 550), rotation speedof the auxiliary cleaning tools 110 is increased (560). As a result, theedge at which two walls intersect can be rapidly cleaned.

Also, when the wall tracing manner is finished (YES in 570), theauxiliary cleaning tool 110 is retracted (580).

FIG. 21 is a flowchart briefly illustrating a control method when therobot cleaner 1 according to the embodiment described in FIGS. 8A and 8Bpasses an excessively dusty region.

The robot cleaner 1 senses dust present in a travel path (610). At thistime, any travel path or cleaning mode of the robot cleaner 1 may beused without limitation. The sensing of dust is performed by a dustsensor present in the dust inlet 33.

Whether or not the amount of sensed dust is a predetermined referencevalue or more is determined (620). The amount of dust may be determinedfrom an amount of light received by the light-receiving unit of the dustsensor and a user or designer can set a predetermined reference valuethrough experiments or statistics.

As a result of determination, when the amount of sensed dust is apredetermined reference value or higher (YES in 620), the region isconsidered to be an excessively dusty region (630), and extension andretraction of auxiliary cleaning tools 110 are repeated at predeterminedintervals (640). As a result, dust can be effectively swept, dispersedor wiped and the excessively dusty region may be informed of a user.

FIG. 22 is a flowchart illustrating a method for controlling the robotcleaner according to the embodiment described in FIGS. 18A and 18B.

In the method for controlling the robot cleaner according to theembodiment of FIGS. 18A and 18B, the first cleaning mode or secondcleaning mode is set based on user commands and obstacle sensingresults. In the embodiment of FIG. 22, the cleaning mode is set based onthe user command.

Referring to FIG. 22, first, whether or not a cleaning start command isinput is determined (710), and selection of the cleaning mode is inputfrom a user when the cleaning start command is input (YES in 710) (720).

When the user selects a first cleaning mode (YES in 720), the auxiliarycleaning tool 110 is retracted (740). Also, the robot cleaner travels ina predetermined travel pattern or a random manner and presence of anobstacle around the robot cleaner 1 is determined (750). At this time,the obstacle may be present in front or rear of the robot cleaner 1.

When an obstacle is determined to be present around the robot cleaner 1(YES in 750), the auxiliary cleaning unit is extended (760). As aresult, the edge at which the obstacle contacts the floor can also bethoroughly cleaned.

Also, after the robot cleaner 1 passes the obstacle (YES in 770), theauxiliary cleaning tool 110 is retracted again (780).

Unless a cleaning finish command is input (NO in 790), obstacle sensingis determined again and the following process is repeated.

When the user selects the second cleaning mode (NO in 730), theauxiliary cleaning tool 110 is extended (840). The extended auxiliarycleaning tool 110 cleans a wide area of the cleaning region, not edgeregions.

When an obstacle is determined to be present around the robot cleaner 1(YES in 850), the auxiliary cleaning tool 110 is retracted again (860).As a result, rapid cleaning can be performed throughout the cleaningregion.

Also, after the robot cleaner 1 passes an obstacle (YES in 870), theauxiliary cleaning tool 110 is extended again (880). Also, unless acleaning finish command is input (NO in 890), the robot cleaner 1determines whether or not the robot cleaner 1 senses the obstacle duringtravel and repeats the following operations.

When a cleaning mode is set according to obstacle sensing results, therobot cleaner 1 senses obstacles present in the cleaning region duringtest travel for setting the map and calculates the number of obstacles,based on the sensing results. When the number of calculated obstacles isa predetermined reference value or more, the second cleaning mode inwhich cleaning is performed throughout the cleaning region, rather thanthe edge of the obstacle is set and cleaning is controlled according tothe second cleaning mode as shown in FIG. 22.

When the number of calculated obstacles is smaller than a predeterminedreference value, a first cleaning mode in which cleaning is performed inthe edge of the obstacle is set and cleaning is controlled according tothe first cleaning mode as shown in FIG. 22.

As described in FIG. 19, control of the robot cleaner in the excessivelydusty region may be applied in any travel mode or cleaning mode and mayalso be applied to a method for controlling the robot cleaner accordingto the embodiment of FIGS. 18A and 18B. Accordingly, the dust sensorsenses dust in a travel path according to the first cleaning mode orsecond cleaning mode during travel and, when the amount of sensed dustis a predetermined reference value or more, extension and retraction ofthe auxiliary cleaning tool 110 are repeated at predetermined intervals,thereby efficiently removing dust and informing a user of the same.

Although the auxiliary cleaning tools 110 are realized in the form of abrush and perform cleaning by sweeping or dispersing foreign matter suchas dust in the aforementioned embodiments, when auxiliary cleaning tools110 are realized in the form of a floorcloth, they perform cleaning bywiping foreign matter with the floorcloth, and when auxiliary cleaningtools 110 are realized in the form of a suction device, they performcleaning by absorbing foreign matter. The type or cleaning method of theauxiliary cleaning tools 110 is not limited and various embodiments maybe used.

In a robot cleaner and a control method for the same according toembodiments of the present disclosure, an auxiliary cleaning tool isextended when the robot cleaner travels in a wall tracing manner, toefficiently clean portions, which a main brush does not reach, such asportions in which obstacles or walls contact the floor or portions inwhich wall surfaces contact one another, and the auxiliary cleaning toolis retracted while the robot cleaner travels inside the cleaning regionin a wall tracing manner to improve efficiency of cleaning.

Also, in a robot cleaner and a control method for the same according toone aspect, extension and retraction of auxiliary cleaning tools arecontrolled according to user commands or environments of cleaningregions. As a result, cleaning that satisfies the user commands orenvironments of cleaning regions can be realized.

Although a few embodiments of the present disclosure have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the disclosure, the scope of which is definedin the claims and their equivalents.

What is claimed is:
 1. A robot cleaner for removing foreign matter froma floor while traveling on the floor, comprising: a body; a main brushunit mounted to a bottom of the body of the robot cleaner; a pluralityof auxiliary cleaning units mounted to the bottom of the body of therobot cleaner, each being protrudable outward from the body of the robotcleaner to a protruded position and retractable into the body of therobot cleaner to a retracted position; and a control unit configured tocontrol the robot cleaner to travel in a wall tracing manner of travelalong a periphery of a cleaning region, and extend at least one of theauxiliary cleaning units from the retracted position thereof to theprotruded position thereof in response to determining that the robotcleaner has been set to travel in the wall tracing manner of travel. 2.The robot cleaner according to claim 1, wherein the control unit extendsonly an auxiliary cleaning unit present on a wall surface from among theauxiliary cleaning units from the retracted position thereof to theprotruded position thereof, in response to determining that the robotcleaner has been set to travel in the wall tracing manner.
 3. The robotcleaner according to claim 1, wherein the control unit controls a speedof the robot cleaner when traveling in the wall tracing manner to belower than another speed of the robot cleaner when travelling in aninner portion of the cleaning region.
 4. The robot cleaner according toclaim 1, further comprising: an obstacle sensor to sense an obstacle inthe cleaning region of the robot cleaner.
 5. The robot cleaner accordingto claim 1, further comprising: a dust sensing unit comprising anoptical sensor that senses dust present on the floor of the cleaningregion.
 6. The robot cleaner according to claim 1, wherein the controlunit increases a cleaning speed of the auxiliary cleaning units, inresponse to an obstacle sensor of the robot cleaner detecting a walldisposed in front thereof while the robot cleaner is travelling in thewall tracing manner.
 7. The robot cleaner according to claim 5, whereinthe control unit repeats extension and retraction of the auxiliarycleaning units at predetermined intervals when an amount of dust sensedby the dust sensing unit is greater than or equal to a predeterminedreference value.
 8. The robot cleaner according to claim 1, wherein thecontrol unit extends the auxiliary cleaning unit into an inner portionof the cleaning region in response to detecting an obstacle within theinner portion of the cleaning region to clean around the edge of theobstacle.
 9. The robot cleaner according to claim 1, wherein the controlunit controls a cleaning speed of the auxiliary cleaning unit toincrease or decrease a cleaning time.
 10. The robot cleaner according toclaim 1, wherein the control unit retracts the at least one of theauxiliary cleaning units to the retracted position thereof in responseto the robot cleaner switching from traveling in the wall tracing manneralong the periphery of the cleaning region to travelling in an innerportion of the cleaning region.
 11. A method for controlling a robotcleaner comprising a main brush unit, and auxiliary cleaning units eachbeing protrudable outward from a body of the robot cleaner to aprotruded position and retractable into the body of the robot cleaner toa retracted position, the method comprising: determining whether or notthe robot cleaner has been set to travel in a wall tracing manner oftravel along a periphery of a cleaning region; outwardly extending atleast one of the auxiliary cleaning units from the retracted positionthereof to the protruded position thereof, in response to determiningthat the robot cleaner has been set to travel in the wall tracing mannerof travel; determining whether the robot cleaner is no longer travellingin the wall tracing manner of travel; and retracting the at least oneauxiliary cleaning units to the retracted position thereof in responseto determining that the robot cleaner is no longer travelling in thewall tracing manner of travel.
 12. The method according to claim 11,wherein the outwardly extending comprises: extending only one auxiliarycleaning unit, among the auxiliary cleaning units, that is present on awall surface, from the retracted position thereof to the protrudedposition thereof in response to determining that the robot cleaner hasbeen set to travel in the wall tracing manner.
 13. The method accordingto claim 11, wherein the robot cleaner comprises a control unit thatcontrols a speed of the robot cleaner when traveling in the wall tracingmanner to be lower than another speed of the robot cleaner whentraveling in an inner portion of a cleaning region to be cleaned by therobot.
 14. The method according to claim 11, further comprising: sensingobstacles disposed in front of the robot cleaner, increasing a cleaningspeed of the auxiliary cleaning units is increased, in response to awall disposed in front of the robot cleaner being sensed while the robotcleaner is travelling in the wall tracing manner.
 15. The methodaccording to claim 11, further comprising: sensing dust disposed in acleaning region to be cleaned by the robot; and repeating extension andretraction of the auxiliary cleaning units at predetermined intervalswhen an amount of dust sensed by the dust sensing unit is greater thanor equal to a predetermined reference value.
 16. The method according toclaim 11, wherein the robot cleaner comprises a control unit configuredto extend the at least one of the auxiliary cleaning units from theretracted position thereof to the protruded position thereof in responseto detecting that an obstacle is present in a cleaning region to becleaned by the robot.